Ground Station

  Ground Station means all facilities in order to communicate with satellite in space. The major role of the ground station is to keep link the communication with satellite in space. It is also very important role. We have Ground Station at Funabashi campus in Nihon University. This page introduce the facilities and the software of our Ground Station.

Facilities / Software

Operating Software

  Ground station software consist of six softwares (Orbital Analysis Software, Uplink Software, Downlink Software,Datebase Software, Attitude Analysis Software, Battery Simulator). It is necessary to operate the satellite. These software will enable to calculate the orbit, attitude, and residual battery of satellite, to send and receive the command and to process of receive data. Please see the following and individual details.

Software Details

Orbit Analysis Software / Uplink Software / Downlink Software
Database Software / Attitude Analysis Software / Battery Simulator

Orbit Analysis Software


  SEEDS that will encircle about the high degree 650 the km encircles the earth about 98 minutes.The electric wave have the characteristic of going straight,the time is limited to communicate in the times one time,in the worst case we will not communicate to satellite.Even if it is the maximum, it is about 15 minutes in the limited time,we have a chance to communicate a day 5 and about six times.To operate a satellite,we should learn when the chance comes.Because we should communicate a satellite.To learn the chace,we should predict where SEEDS and when SEEDS enters the range of visible.

  Also, it is necessary to always turn the antenna to SEEDS because the directional antenna is used to communicate efficiently with SEEDS, and it is necessary to know which direction SEEDS is now.

  Moreover,the Doppler effect of the electric wave occurs because SEEDS is turned on to the orbit that moves in number km of per second. We might hear, the Doppler effect's being felt familiar hear the blast of a sirens higher than usually when the ambulance is approaching, and it be a case of hearing the blast of a siren low it is in away. This is the frequency of the sound wave whether is high or low.Because this phenomenon comes to the electric wave, it is necessary to always shift the communication frequency to communicate with SEEDS.


  Then, to meet these demands, the orbit is calculated beforehand in our Grand station.The orbit calculation can be done comparatively easily by using the orbit data of NASA Two Line Format that the volunteer group of NORAD(North American Aerospace Defense Command) is offering. The orbit calculation software develops with VB,simply calculates the orbit, calculates the orbit by SGP4,controls an automatic frequency of wireless machine and controls Antenarortata automatically. Also,the software has the function that estimates the amount of battery remainder of SEEDS,displays for which direction antenna of rooftop point at with CG,caluclates the orbit of sun.

You can get the Orbit data


Uplink Software

  The uplink software makes the uplink command to give the commandment and send to SEEDS on the orbit. The uplink software makes a digital signal to control SEEDS made with the personal computer. And, the digital signal is converted into the analog voice signal and TNC(Terminal Node Controller) that transmits the analog voice signal from the transmitter is controlled. The commands are combined and the up-link command is made which commandment when to execute to manage SEEDS from the ground.

  For example,when we want to operate digitalker for 300 seconds,

  • 15 seconds after it uplinks it|Stop to send the CW
  • 16 seconds|Voice reproduction
  • 316 seconds|Voice stop
  • 317 seconds|Send the CW housekeeping data

The uplink software of uplink command makes it.SEEDS executes the commandment when the uplink command is received and reproduces digitalker. Uplinked tasks of about three and a half hours are memorized, and SEEDS can be executed.Using this function,we can operate the mission anywhere after it up-links between times two times of orbit.

Please see here about the list of the command of detailed SEEDS.


Downlink Software

  Various data of a state of the system, an electric power, an external temperature, an internal temperature, and posture, etc. as housekeeping data (CW) and mission data (FM) is transmitted from SEEDS as CW and FM packet.Then, it was necessary to develop software that was able to receive those data by the automatic operation, and was able to see in real time though those data had to be received, to be preserved, and to analyze it in the ground station.

  This software is software done for the ground station member to learn the state of the satellite by receiving the binary data that the down link is done from the satellite, and converting data in real time. And, acquired data is preserved, and it is possible to pass it to the database software.

  There are two kinds of data of the housekeeping data and the mission data that the down link is done from the satellite, and, in addition, those two kinds of data is divided into a lot of patterns according to the situation and the necessity of the satellite. This software receives, is data conversion, and can preserve any data by the automatic operation.

  Visual Basic is used from the easiness of the treatment as a development language.

CWf[^ DownlinkSoftware1
FMf[^ DownlinkSoftware2

Database Software  


  The housekeeping data and mission data obtained from SEEDS becomes huge.These data is not obtained in a Nihon University ground station alone but is obtained by the cooperation of the earth station of another university and amateur radio operator's people.Also, there is not only the housekeeping data and mission data but also each operation data of the data of the up-link software, and it is necessary to manage data neatly.

  Data base software (puxos) is software that stores all these data, retrieves necessary data at necessary time, and makes the data file. And, it is done to annul the housekeeping data mission data that broke when receiving it, and to send the operation data to receive these data again to the uplink software.


Attitude Analysis Software  


  under construction of detail page .


Battery Simulator  

|Arc ver.2|

  under construction of detail page .